摘要:
The complexes [{Ru(tpy*)(bpy)}(2)(mu-adpc)][PF6](2) where tpy* is 4,4',4"-tri-(tert-butyl)-2,2':6',2"-terpyridine, bpy is 2,2'-bipyridine, and adpc(2-) is 4,4'-azo-diphenyleyanamide dianion and trans, trans-[{Ru(tpy*)(pc))(2)(mu-adpc)] where pc(-) is 2-pyrazine-carboxylato were prepared and characterized by cyclic voltammetry and spectroelectrochemical methods. Intervalence band properties and IR spectroelectrochemistry of the mixed-valence complexes [{Ru(tpy*)(bpy)}(2)(mu-adpc)](3+) and trans, trans-[{Ru(tpy*)(pc)}(2)(mu-adpc)](+) are consistent with delocalized and valence-trapped mixed-valence properties respectively. The reduction in mixed-valence coupling upon substituting a bipyridine ligand with 2-pyrazine carboxylato strongly suggests that hole-transfer superexchange is the dominant mechanism for metal-metal coupling in these complexes. (c) 2007 Elsevier B.V. All rights reserved.